Yale-New Haven Hospital’s security force will lose its power to make arrests in July, Mayor John DeStefano Jr. said a letter to hospital officials last week.

The letter, which DeStefano sent Thursday, upholds a recommendation made by the Board of Police Commissioners in December. City officials and pro-union activists began challenging the hospital’s arrest powers in September after Yale-New Haven security officers arrested eight leafletters who were distributing pro-union material on hospital grounds.

The letter expressed concern that the hospital’s constables were not accountable to the city, said hospital spokeswoman Katie Krauss. Krauss said the hospital was disappointed by the mayor’s decision in light of a series of proposals the hospital made in January in response to the board’s recommendation.

“We didn’t really get a response about the proposals, we just got a ‘No’ from the mayor,” Krauss said. “There was no official contact for almost two months, so that was a surprise and a bit of a disappointment.”

But the mayor’s executive assistant, Julio Gonzalez ’99, said DeStefano made his decision after discussions with both the hospital and city officials. Gonzalez said the timing of the letter was unrelated to the strike of dietary employees at the hospital, which is scheduled to begin today. Since the changes will not be implemented until the termination of a prior agreement on July 1, the mayor’s decision will have no effect on the hospital’s arrest powers this week.

State law permits the mayor to delegate arrest powers to private entities. Krauss said the hospital currently employs 54 security officers, many of whom are former New Haven police officers. She also said the officers make about 25 or 30 arrests per year, typically on charges of domestic violence or criminal trespassing.

The trespassing charges against the leafletters were dropped in November, but not before a flurry of public criticism that resulted in an aldermanic resolution calling for the revocation of the arrest powers.

Ward 1 Alderman Ben Healey ’04, who drafted the resolution, said the mayor’s decision recognized the potential for abuse of the constabulary privilege.

“He’s demonstrating at a critical time that the administration of the hospital cannot use powers delegated by the city to intimidate its workers,” Healey said. “The door’s not closed to finding a way to integrate the constables into a more accountable system, but the hospital has to step up if it wants to see that happen.”

In the letter sent to the mayor in response to the board’s recommendations, hospital president Joseph Zaccagnino said the hospital would agree to subject the constables to greater oversight by the New Haven Police Department. The first of his proposals — the creation of a liaison officer between the hospital and the NHPD — was recently implemented by New Haven Police Chief Melvin H. Wearing.

State Rep. Patricia Dillon said the current policy could leave New Haven liable for wrongful arrests made by the hospital. Dillon said she supported a bill in the General Assembly last year that would prohibit cities from delegating arrest powers to private corporations.

“There’s no chain of command,” Dillon said. “Giving that kind of power to a private company almost invites abuse.”

But Ward 26 Alderwoman Lindy Gold said delegating arrest powers to the hospital provides a stabilizing force in the neighborhood. She said the recent condemnation of the constables’ behavior was sparked by a conflict between the Fraternal Order of Police, which represents the security force, and the AFL-CIO, which has supported the unionizing drive of hospital workers.

“I absolutely don’t think that those arrest powers should have been taken away,” Gold said. “I think this is about union competition, not about real issues.”